The present invention relates to a process for the production of oxiranes from ketones.
Processes for the production of oxiranes from ketones under aqueous conditions are known. For example, Shiraki, et al, "Anion-catalyzed Phase-transfer Catalysis. II. Effects of Anionic Tetrakis[3,5-bis(trifluoromethyl)phenyl]borate Catalyst in Phase-transfer-catalyzed Sulfonium Ylide Formation", Bull. Chem. Soc. Japan, Vol.58, pages 3041-3042 (1985) discloses use of tetrakis[3,5-bis(trifluoromethyl)phenyl]borate anion to promote formation of oxiranes from carbonyl substrates and trimethylsulfonium chloride in a two-phase mixture of dichloromethane and up to 50 wt % aqueous solutions of sodium hydroxide.
Merz et al, "Phase-transfer-catalyzed Production of Sulfur Ylides in an Aqueous System", Angew.Chem.Internat.Edit., Vol. 12, pages 845-846 (1973) discloses the use of tetrabutylamonium iodide in a two-phase system of dichloromethane and aqueous sodium hydroxide to produce oxiranes from aldehydes. This report also teaches that good yields of oxirane are not obtained when ketones rather than aldehydes are used as the starting material.
Hatch, "The Synthesis of Oxiranes from Aqueous Solutions of Simple Alkyl, Allyl, and Benzylsulfonium Salts", Journal of Organic Chemistry, Vol. 34, pages 2133-2137 (July 1969) describes the results obtained when simple sulfonium salts react with warm aqueous sodium hydroxide and carbonyl compounds to produce oxiranes. The results indicate that the oxirane yield obtained from various aldehydes is substantially dependent upon the specific type of sulfonium salt used. The results also led Hatch to conclude that reactions of the type disclosed therein are subject to structural factors (i.e., structural differences in reactants are significant), reaction conditions, and the possibility for side reactions.